Tufa (pronounced toofa) is a type of porous volcanic stone that can be found regionally in the American Southwest. It's widely available on the Navajo reservation. Casting jewelry using a mold hand-carved of the volcanic tufa material is a traditional jewelry making technique developed by some of the first Navajo silver makers in the 1870's. According to Washington Matthews, whose observations on Navajo Silversmiths were published in the Second Annual Report to the Smithsonian Institution from the Bureau of Ethnology, 1880-1881, "they cut molds from soft sandstone and poured melted ingots into these hollows for casting."
To create a tufa cast piece of jewelry is a precise and lengthy process. Native American artisans first source tufa rock by cutting it from their special,
sometimes secret local cache. They then cut the block of tufa in two pieces, which fit tightly together forming a mold. Into one or both sides of the soft tufa stone mold, the native jewelers skillfully carve patterns, sometimes quite complex. They also carve air holes and an area at the top of the mold, where molten metal (most often silver) will be carefully poured in once melted to the proper point. When the metal has cooled and hardened into the shape of the mold, the two sides of the carved tufa block can be opened to reveal what is on its way to becoming a piece of jewelry like the Ira Custer ring you see in the photo.
Don’t be misled by the term tufa-casting to believe that once created, the mold will repeatedly produce multiple pieces of jewelry in the same pattern. Tufa, and the mold that is carved out of tufa, is a fragile material. Oftentimes, only one piece of jewelry comes from any single tufa mold. Even when a mold can be used more than once, the next pieces of jewelry to come from the mold will inevitably have variations.
Navajo silverworker Grey Moustache, who was interviewed by John Adair for his book The Navajo and Pueblo Silversmiths, speaks of the fragility of tufa casting: ". . . forty years ago (1898), when I made a trip up to Sunrise Springs. I saw some white rock on the side of a hill and I thought that it might make good molds for my silver, so I got some of it and made a cast for a ketoh. But that stone was too soft and cracked all to pieces. Then I went back a second time and got some more, and this time the stone was just hard enough, and I made a good ketoh in that mold."
Today, some Navajo and Pueblo jewelers still tufa cast their work. Navajo artist Ira Custer is one of these modern-day silverworkers creating in the old style. An expert in the technique, we would like to thank him for providing us with these photos of his tufa casting process.
We're so fond of this historic Native American method of creating tufa cast jewelry, and we love the resulting pieces it makes.